package com.fyzk.utils;

import java.io.ByteArrayOutputStream;
    
public class Base64 {  
     private static char[] base64EncodeChars = new char[] {  
         'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H',  
         'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P',  
         'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X',  
         'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f',  
         'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n',  
         'o', 'p', 'q', 'r', 's', 't', 'u', 'v',  
         'w', 'x', 'y', 'z', '0', '1', '2', '3',  
            '4', '5', '6', '7', '8', '9', '+', '/' };  
    
     private static byte[] base64DecodeChars = new byte[] {  
         -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,  
         -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,  
         -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -1, -1, 63,  
         52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -1, -1, -1,  
         -1,  0,  1,  2,  3,  4,  5,  6,  7,  8,  9, 10, 11, 12, 13, 14,  
         15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, -1,  
         -1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40,  
         41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, -1, -1, -1, -1, -1 };  
    
     private Base64() {}  
    
     public static String encode(byte[] data) {  
         StringBuffer sb = new StringBuffer();  
         int len = data.length;  
         int i = 0;  
         int b1, b2, b3;  
    
         while (i < len) {  
             b1 = data[i++] & 0xff;  
             if (i == len) {  
                 sb.append(base64EncodeChars[b1 >>> 2]);  
                 sb.append(base64EncodeChars[(b1 & 0x3) << 4]);  
                 sb.append("==");  
                 break;  
                 }
             b2 = data[i++] & 0xff;  
             if (i == len) {  
                 sb.append(base64EncodeChars[b1 >>> 2]);  
                 sb.append(  
                         base64EncodeChars[((b1 & 0x03) << 4) | ((b2 & 0xf0) >>> 4)]);  
                 sb.append(base64EncodeChars[(b2 & 0x0f) << 2]);  
                 sb.append("=");  
                 break;  
                 }  
             b3 = data[i++] & 0xff;  
             sb.append(base64EncodeChars[b1 >>> 2]);  
             sb.append(  
                     base64EncodeChars[((b1 & 0x03) << 4) | ((b2 & 0xf0) >>> 4)]);  
             sb.append(  
                     base64EncodeChars[((b2 & 0x0f) << 2) | ((b3 & 0xc0) >>> 6)]);  
             sb.append(base64EncodeChars[b3 & 0x3f]);  
            }  
         return sb.toString();  
     }  
    
     public static byte[] decode(String str) {  
         byte[] data = str.getBytes();  
         int len = data.length;  
         ByteArrayOutputStream buf = new ByteArrayOutputStream(len);  
         int i = 0;  
         int b1, b2, b3, b4;  
    
         while (i < len) {  
    
             /* b1 */  
             do {  
                 b1 = base64DecodeChars[data[i++]];  
             } while (i < len && b1 == -1);  
             if (b1 == -1) {  
                 break;  
                 }  
    
             /* b2 */  
             do {  
                 b2 = base64DecodeChars[data[i++]];  
             } while (i < len && b2 == -1);  
             if (b2 == -1) {  
                 break;  
                 }  
             buf.write((int) ((b1 << 2) | ((b2 & 0x30) >>> 4)));  
    
             /* b3 */  
             do {  
                 b3 = data[i++];  
                 if (b3 == 61) {  
                     return buf.toByteArray();  
                      }  
                 b3 = base64DecodeChars[b3];  
             } while (i < len && b3 == -1);  
             if (b3 == -1) {  
                 break;  
                 }  
             buf.write((int) (((b2 & 0x0f) << 4) | ((b3 & 0x3c) >>> 2)));  
    
             /* b4 */  
             do {  
                 b4 = data[i++];  
                 if (b4 == 61) {  
                     return buf.toByteArray();                   }  
                 b4 = base64DecodeChars[b4];  
             } while (i < len && b4 == -1);  
             if (b4 == -1) {  
                 break;  
                 }  
             buf.write((int) (((b3 & 0x03) << 6) | b4));  
            }  
         return buf.toByteArray();  
     }  
}
